JPH06121451A - Protective relay - Google Patents

Abstract

PURPOSE:To enable sequential interruption of loads from time when the level of frequency lowering is small, by changing the order of interruption using a judged result on whether there is any object to be interrupted. CONSTITUTION:Whether there is any load being an object to be interrupted is judged, and an interruption order changing part 15 changes the order of interruption using the judged result. And, loads are interrupted by the result. Namely, the order of interruption is advanced (changed) at the interruption order changing part 15 as, a load to be able to be interrupted at a first frequency lowering level, a load to be able to be interrupted at the next frequency lowering, etc., by using the judged result for learning objects to be interrupted from ON/OFFs of circuit-breakers CB1-CB4. Consequently, it becomes possible to perform sequential interruption of loads always from time when the level of frequency lowering is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective relay device for switching the load cutoff order when a system frequency is abnormal due to a power system accident.

[0002]

2. Description of the Related Art When an accident occurs in a power system, an abnormality in the system frequency is predicted. FIG. 3 is a block diagram of a conventional protective relay device that detects such a system frequency abnormality. The operation will be described below with reference to FIG.

The protective relay device 1 inputs the bus voltage v to the frequency detection relays 11A and 11B and detects the frequency of the system. One frequency detection relay 11A operates when the frequency of the system drops to f1 or less, and does not operate when the frequency is f1 or more. The operation output of the frequency detection relay 11A is input to the timer 12A at the next stage, and is output for a fixed time t1.
It operates after a lapse of seconds and the output becomes T1 = 1.

On the other hand, the frequency detection relay 11B operates when the frequency of the system drops below f2, and the frequency becomes f2.
In the above cases, it becomes inoperative. This frequency detection relay 11
The operation output of B is input to the timer 12B of the next stage, operates after a lapse of a fixed time t2 seconds, and the output becomes T2 = 1. here,
The system frequency f1> the system frequency f2.

By the way, the object of interruption is the contact point CB of the circuit breaker.
1, CB2, CB3, CB4. That is, if any of the circuit breakers CB1 and CB2 is turned on, O
The output L1 of the R circuit 13A becomes 1. This condition and the output T1 = 1 of the timer 12A are input to the AND circuit 14A in the next stage, and when the AND condition is satisfied, the cutoff 1 = 1 and the cutoff command is output. Similarly, if any of the circuit breakers CB3 and CB4 is turned on, the output L2 of the OR circuit 13B becomes 1 and
It is input to the AND circuit 14B at the next stage. When the AND condition with the output T2 = 1 of the timer 12B is satisfied, the AND circuit 14
Blocking 2 = 1 from B, and the blocking command is output. The breaker CB1, CB2 or CB3, CB4 corresponding to the break target is pulled out and opened by the command of break 1 or break 2.

The above operation is shown in the time chart of FIG. That is, when the frequency f0 of the electric power system in the normal state drops to f0 → f1 → f2 due to a system fault, the frequency detection relay 11A operates at f1 or less. This operation detects the continuation of the constant time t1 by the timer 12A at the next stage. At this time, if any of the circuit breakers CB1 and CB2 is turned on, the timer 12A
When the AND condition with the operation output is satisfied, the breaking 1 command is output, and the circuit breakers CB1 and CB2 are pulled out and opened from the on / off state.

Further, if the frequency drops below f2,
The frequency detection relay 11B operates. This operation detects the continuation of the constant time t2 by the timer 12B in the next stage. At this time, if any of the circuit breakers CB3 and CB4 is turned on, the timer 1
When the AND condition with the operation output of 2B is satisfied and the breaking 2 command is output, the circuit breakers CB3 and CB4 are pulled out and opened from the on / off state. As a result, the system frequency is restored to f0 at the normal time before the system accident.

[0008]

As described above, the conventional method is the order cutoff method in which the load is fixed according to the frequency reduction level. Therefore, if there is no load corresponding to the cutoff at the frequency reduction level f1, the cutoff effect cannot be obtained.
Further, even if the load corresponding to the cutoff is cut off at the next frequency reduction level f2, the cutoff effect is low and the system frequency does not return to the original value.

The present invention has been made in order to solve the above problems, and an object thereof is to provide a protective relay device having a function of switching the order of interruptions by using the judgment result of presence / absence of interruption object. is there.

[0010]

In order to achieve the above object, the present invention provides a frequency abnormality by shutting off a load or a generator when a frequency abnormality occurs in the system due to the occurrence of a power system accident or when the abnormality is predicted. In the protective relay device for recovering the load, a judging means for judging the presence or absence of a load or a generator, a switching means for switching the shutoff order from the judgment result obtained by the judging means, and a load or a power generation depending on the result of the switching means. And a shutoff means for shutting off the machine.

[0011]

According to the protective relay device of the present invention, the load can be interrupted at the first frequency lowering level and the load can be interrupted at the next frequency lowering level by using the interrupting target switching result of the circuit breaker ON / OFF in the interrupting order switching unit. By increasing (switching) the order of cutoff like load, it is possible to cut off the load in order from the time when the frequency reduction level is always small.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a protective relay device 1 according to an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 3 are designated by the same reference numerals. The structural feature is that a blocking order switching unit 15 that switches the blocking order using the determination result of the blocking target is provided.
It is composed of circuits 152A, 152B, 152C and 152D and OR circuits 153A and 153B. Since other configurations are the same as those of the conventional example, the same parts are designated by the same reference numerals and described. Next, the operation of this embodiment will be described.

Contact information of the circuit breakers CB1, CB2, CB3, CB4 is input to the OR circuits 13A, 13B, and if any of the circuit breakers is turned on, the output L of the OR circuits 13A, 13B.
1, L2 = 1 is input to the cutoff order switching unit 15 in the next stage. In the interruption order switching unit 15, the interruption order is switched based on the decoding of the L1 and L2 signals and the decoding result.

First, the decoder 151 decodes the cutoff object from the L1 and L2 signals. FIG. 2A is a truth table of the decoder 151. That is, when the combination (0, 1, 2, 3) of the two signals L1 and L2 is decoded and the combination is 0, Y0
= 1, when the combination 1 is Y1 = 1, when the combination 2 is Y2 = 1,
In the case of combination 3, Y3 = 1 is output.

Next-stage AND circuits 152A, 152B, 1
The 52C and 152D receive the signal from the circuit at the previous stage and perform the next operation. The AND circuit 152A satisfies the AND condition with the operation signal T1 = 1 of the timer 12A and the output signal Y1 = 1 of the decoder 151, and the output signal is the OR circuit 1 of the next stage.
It is input to 53A and the cutoff 1 command is output. The AND circuit 152B satisfies the condition with the operation signal T1 = 1 of the timer 12A and the output signal Y2 = 1 of the decoder 151, and the output signal is input to the OR circuit 153B at the next stage and the cutoff 2 command is output. The AND circuit 152C satisfies the condition with the operation signal T1 = 1 of the timer 12A and the output signal Y3 = 1 of the decoder 151, and the output signal is input to the OR circuit 153A of the next stage and the cutoff 1 command is output. The AND circuit 152D is satisfied by the operation signal T2 = 1 of the timer 12B and the output signal Y3 = 1 of the decoder 151, and the output signal is the OR circuit 1 of the next stage.
It is input to 53B and the cutoff 2 command is output.

That is, when only the signal L2 is present in the combination of the output signals L1 and L2 from the OR circuits 13A and 13B, the interruption order is advanced by one and the interruption condition is switched from the timer 12B to the timer 12A. Figure 2
(B) shows a list of interruption targets and corresponding timers. Signal L
In the case of a combination in which only 1 or L2 exists, the timer 12A is applicable. In the case of a combination in which all signals L1 and L2 exist, the signal L1 is the timer 12A and the signal L2 is the timer 1.
2B is applicable. By thus advancing the order of interruption, it is possible to prevent the omission of the interruption target of the order interruption and prevent the deterioration of the control effect.

[0018]

As described above, according to the present invention, the load to be cut off which is fixedly handled according to the frequency reduction level is cut off in order, but the load is cut off by deciphering the judgment result of the presence or absence of the cutoff target. Since the order of interruption targets can be switched (advanced) in the descending order of the order, the loads can be interrupted even when the frequency reduction level is slight. That is, by switching the load cutoff order to cut off the load, it is possible to provide a protective relay device having an extremely excellent control effect.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a protective relay device according to an embodiment of the present invention.

FIG. 2A is a truth table of a decoder, and FIG.
Is a list of interrupt targets and corresponding timers.

FIG. 3 is a block diagram of a conventional protective relay device.

FIG. 4 is a time chart of the conventional protective relay device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Protective relay device, 11A, 11B ... Frequency detection relay, 12A, 12B ... Timer, 15 ... Breaking order switching part,
CB1 to CB4 ... Circuit breakers.

Claims (1)

[Claims] 1. A protective relay device for recovering an abnormal frequency by shutting down a load or a generator when the frequency of the system is abnormal due to an accident in the power system or when the abnormality is predicted. It is characterized by further comprising: determination means for determining the presence / absence, switching means for switching the order of interruption based on the determination result obtained by the determination means, and interruption means for interrupting the load or the generator depending on the result of the switching means. Protection relay device.